Data sources, such as video cameras, are often linked to a remotely located data destination, such as a data storage or processing facility, by an optical and/or electrical connection. For data sources that move or rotate (for example, a remotely articulated rotatable dome-type video camera), the linkage between the data source and the data destination can include a rotary coupler connected to a fiber or cord. The rotary coupler prevents the fiber or cord from becoming twisted as the data source moves or rotates with respect to the data destination.
Typical rotary couplers, for example those described in U.S. Pat. Nos. 4,124,272 and 5,039,193, are passive; that is, the couplers do not include electronic components requiring electricity. The passive couplers described in these patents use lens relay optics and mechanical tolerance control to reduce signal degradation caused by transmission of the signal across the rotary junction. In other optical rotary couplers, such as those described in U.S. Pat. No. 5,007,697, the optical signal is converted to an electrical signal to facilitate transmission across the rotary junction. In still other optical rotary couplers, the dimensions and tolerances of coupler components are tightly controlled to minimize signal degradation by dispersion or mode launch effects caused by misalignment of optical coupler components.